What Happens If US Troops Run Into Iranian Military in Iraq?

On the heels of President Obama's announcement that up to 300 U.S. military advisers will be sent to Iraq to help combat the threat from a Sunni terror group, an awkward question was raised: What happens if the U.S. troops, many of them Special Forces, run into Iranian soldiers who are reportedly already in Iraq in numbers?

The question was first posed to ABC News Thursday, shortly after President Obama's announcement, by a former member of U.S. special operations who knows some of the men on their way to Iraq. The former soldier said he was concerned the U.S. troops at the ground level may not have been given guidance from higher up for that specific possibility. White House National Security Council representatives and a Defense Department official did little to ease that concern in conversations with ABC News Thursday evening.

The Wall Street Journal first reported last week that Shiite-dominated Iran had deployed units from its powerful Revolutionary Guard to Iraq to help protect Baghdad and holy Shiite sites, citing Iranian security officials. Early this week, the paper reported a member of Iran's elite Quds Force had purportedly died fighting there. Top Iranian officials, including President Rouhani, have strongly denied they have forces in Iraq, but in a lengthy email exchange with ABC News, the representatives of the U.S. National Security Council and the Pentagon did not question the Iranian military's presence there. If there are Iranian troops in Iraq, what happens if U.S. soldiers find themselves face-to-face with troops from the nation President Obama's predecessor once put squarely in the "axis of evil"?

When asked directly if the soldiers on their way to Iraq had been given specific guidance, NSC staffer Bernadette Meehan told ABC News, "We have been clear about the role of any U.S. personnel in Iraq. We have also been clear about any possible interaction with Iran on the topic of Iraq."

Secretary of State John Kerry said Monday the U.S. is "open to discussions" with the Iranians concerning Iraq's security "that could minimize the violence, hold Iraq together, the integrity of the country, and eliminate the presence of outside terrorist forces." President Obama said Thursday Iran could play a constructive role in Iraq, as long as it does not come in only as an armed force backing the Shiite-led government.

However, the same day as Kerry's statement, Pentagon spokesperson Rear Admiral John Kirby told reporters there are no plans to coordinate military activities with Iran in Iraq.

Meehan didn't say if any of the high-level statements translated to orders for the few soldiers actually putting boots on the ground, and instead deferred to the Defense Department. In a subsequent interview, a Defense Department official told ABC News that Kirby's statement reflected U.S. military policy from top officials to the very bottom.

"The Department of Defense does not have any direct engagement with Iranian forces of any kind," said the official, adding that any potential coordination with the Iranians would come from the State Department, presumably well above the pay grades of the men on the ground.

Like Meehan, however, the official declined to say whether the policy translated into actual orders about what American troops should do if they ran into Iranian troops, beyond saying that in the "unlikely, hypothetical scenario" all U.S. government employees have "very clear guidelines... on possible interactions with Iranian government officials."

Anyway, the defense official said, the idea that U.S. soldier would necessarily interact with the Iranians was based on an "oversimplification" of the situation that ignored "a long history of much more extensive on the ground involvement and partnered operations [by the U.S.] in advising and assisting Iraqi security forces" with Iranian forces around.

"They were there in the years that we were there," the official said, referring to the years after the U.S. invasion of Iraq in 2003, "and we managed to conduct our mission without getting into the situation that you're addressing in your inquiry."

The official said that historically, Iran has been involved with Iraqi militias, rather than its proper military, lessening the likelihood of U.S.-Iranian overlap.

However, the official acknowledged that the mission this time -- with the U.S. and Iran both supporting the Iraqi government against an organized enemy, Islamic State of Iraq and Syria (ISIS), potentially in a defense of the same cities, namely Baghdad -- is different.

Another former U.S. soldier with recent experience in Baghdad was skeptical of the Defense Department's position.

"I'm sure they [the U.S. and Iran] will have to cooperate on some level, even if it's just them leaving us alone in a mutual understanding," the ex-soldier told ABC News.

Beyond either avoiding each other altogether or some potential cooperation, there is another chilling possibility, however slight, that the armed men from the U.S. and Iran could get into a violent confrontation of their own.

In that case, the U.S. defense official said, "I will just say, our forces have the inherent right to self-defense."